Evidence for Evolution One of the major ways in which scientists can observe evolution is by looking at small-scale evolutionary phenomena. This is known as microevolution. Microevolution describes changes that occur within a population of a single species.
Peppered moth • the peppered moth has undergone a change in it’s population genetics because of human interference. • Studied in England. • Industrial melanism to refers to the genetic darkening of species in response to pollutants.
2. Drug resistant bacteria Example: penicillin - a wonder drug of the 50’s it helped cure many ailments - because of over-prescription and abuse by patients many new mutated forms of bacteria are emerging that are antibiotic resistant
Weak forms destroyed Application of antibiotics Dish with bacterial cultures Increased dosage Isolation of resistant bacterial strains
3. Insecticide Resistance DDT was a lethal form of insecticide to all insects in 1950’s but today 225 species are resistant. One actually uses it for a food source.
More Evidence for Evolution Macroevolution - refers to large scale and long-term evolutionary patterns among many species. • Macroevolution cannot be studied directly. • It is studied by examining patterns in biological populations and groups of related organisms and inferring process from pattern.
1.The Number of Species • There are numerous amounts of species that are very similar in their appearance and in the biological niche they occupy. • These similar animals are modified depending on the area in which they live. • Example: Darwin’s Finches
2. Biogeography • The distribution of plants and animals in the various regions in the world. • Examples: • Why are marsupials found in Australia and not elsewhere? • Why are similar organisms found on coastal shorelines of similar islands?
As Pangea split 220 million years ago mammals were evolving. Australia split from the supercontinent early and it is believed that the ancestor to marsupials was found there. elsewhere they were outcompeted.
3. The Fossil Record • Reveals a succession of living forms, with simpler forms generally preceding more complex forms. • Fossil - any remains, trace, or imprint of a plant or animal that has been preserved in the earth’s crust since some past geologic or prehistoric time.
Transitional Fossils • is the fossil remains of a creature that exhibits certain primitive traits in comparison with its more derived descendants. • Otherwise known as a “Missing Link”.
4. Comparative Anatomy Homologous Structures: Similar structures across species due to common descent, irrespective of the diverse uses to which they may be put.
Opposed to homologous structures are analogous structures. Analogous structures have similar appearance and function, but have evolved from entirely different backgrounds. Often a result of convergent evolution. Example: - Bird’s wings/insect’s wings - Shark fins/whale fins
Convergent Evolution Placental mammals: top row Marsupial mammals: bottom row
5. Embryology • Embryos of mammals all possess a notochord (stiff dorsal rod), gill slits, seven cervical vertebrae, and four limbs.
6. Vestigial Structures • Organs or appendages that are no longer of use, but remain as remnants of evolutionary past. • Examples: - Pelvic bones in whales and snakes - Male nipples - appendix
7. Molecular Biology • Sequencing of DNA and proteins indicates the degree of relatedness between organisms.